1. Technical Field
The invention disclosed broadly relates to raster scanned display presentations of sensor processed data and more particularly relates to a method and apparatus for adding an additional degree of freedom, namely additional information as a hue encoding to an original monochrome presentation.
2. Background Art
Many sensor information processing applications currently use monochrome B-scan presentations to exhibit processing results from radar, sonar, spectral estimation, seismic profiling, radio astronomy, bio-engineering, and infrared imaging. The use of color for such raster display presentations has been limited to the encoding of amplitude values from a fixed set of hue/luminance colors to convey recognition by a human operator.
For some applications, processing for an additional dimension, hue, comes as a standard part of the system signal processing. Doppler for radar and sonar are such applications. In these displays X and Y are usually range and bearing respectively. On the luminance or Z axis, brightness is a relative signal level. A brighter spot indicates the presence of a strong reflector. Doppler processing done independently for each range and bearing cell can be color encoded so that the hue of the bright spot indicates movement or the lack of movement of the reflector towards or away from the source, and the approximate speed of the reflector. This additional information comes from sensor data in real-time or can be stored in a ROM as described in U.S. Pat. No. 4,364,085 to Dalke.
Generation of an orthogonal color or hue dimension for other applications is not as obvious. The presence of a color processor can aid in developing such data in real-time directly by image processing of the monochrome information when normal system processing does not. For example, a useful and orthogonal luminance axis for an infrared presentation can be temperature gradient where the hue axis is left as the temperature level. The image would then indicate directly current temperature, as well as the heating or cooling trend. The image processing to obtain the gradient can be implemented in a color processor by comparison to prior images on a pixel-by-pixel basis. Similarly, the color processor can be used to provide additional information on a moving infrared, acoustic (passive sonar) or electromagnetic source by doing a Hough transform (reference U.S. Pat. No. 3,069,654 to Hough, December 1962) on multiple trajectory hypotheses.
In displays having low signal-to-noise information, the presentations to a sonar or radar operator provides signals that are hard to recognize and the time required for the recognition is long. A significant amount of time and effort is required in operator training to use the display presentations. What is needed is a method and apparatus for adding an additional degree of freedom, additional information as a hue encoding to an original monochrome presentation to allow easy and quick recognition by an operator of target information.